[CP2K-user] [CP2K:17862] Vibrational analysis

[mengchao shi]

Dear all
     I want to calculate the atomic frequency of diamond silicon by CP2K.
     My supercell contains N=8 atoms (a PBC system), and I will get the 
3N=24 frequencies.
      
     However, I only get the  21 frequencies,  The frequencies of the 
rotations  are obtained, but the part of translations are not obtained.

     I use the VASP to calcualte the vibrational analysis, I get the 24 
frequencies.
     I  compare the two results:
    
 VASP: (unit: cm-1,  24 frequencies )    
 513.100912      513.097046       513.092040     
 461.327377       461.230874     461.217489     461.210747     461.189027   
  461.185948
 409.422422        409.414429     409.406072    409.397086     409.393930   
 409.387741  
  140.194017       140.189188     140.187673    140.182783     140.175562  
 140.172242 
    0.006451           0.010431         0.055547 
 
  CP2K: (unit: cm-1,  21 frequencies)    
    515.944308    515.944308     515.944308
    463.042397     463.042397    463.042397    463.042397  463.042397  
   463.042397
    412.993772     412.993772    412.993772     412.993772  412.993772    
412.993772
    139.536054      139.536054    139.536054    139.536054  139.536054    
139.536054
   
    The results are similar, but the number is different, how do I get 24 
frequencies by CP2K.    

   The part input:
    "
     &GLOBAL
      PROJECT system
      RUN_TYPE VIBRATIONAL_ANALYSIS
      PRINT_LEVEL MEDIUM
   &END GLOBAL

    &VIBRATIONAL_ANALYSIS
        NPROC_REP 3
        DX 0.001
        FULLY_PERIODIC .TRUE.
&END VIBRATIONAL_ANALYSIS
       "

       Thank you for your help.
        Best,
        Mengchao.

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